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New Light on Cancer Fight

For their ever-growing arsenal of cancer-fighting tools, doctors may one day have a new, improved type of phototherapy being developed by a team of FSU researchers. Their novel advance, reported in the journal Proceedings of the National Academy of Sciences last year, comes in the form of an engineered molecule that is almost twice as efficient at killing cancer cells as molecules currently used in approved phototherapy techniques. Lab results put the new therapy at 50 percent efficiency versus the 25 to 33 percent garnered by usual methods.

Most phototherapy (also called photodynamic therapy) methods involve injecting a drug into a cancer patient's bloodstream, waiting until the drug is flushed from normal cells but lingering in cancer cells, and beaming a light source into affected tissues. The light activates the drug, which produces a reactive form of oxygen that clips the cell's DNA and destroys it.

Igor Alabugin, FSU associate professor of chemistry and biochemistry, leads the research effort. He said the advantage of phototherapy over some other cancer treatments is that the technique destroys cancer cells while leaving most healthy cells alone. A major problem, however, is that current drugs rely on oxygen to work, and cancer cells don't carry a lot of oxygen to begin with.

Another problem with approved phototherapies is that the drug molecules remain active even after they've done their work. They continue to produce reactive oxygen, which can go on to cause other problems in the body. Albugin's team's molecule solves both problems: it doesn't require oxygen and becomes inactive once it has killed its targeted cells.

The approach exploits an earlier finding that a common, naturally occurring molecule called lysine has the ability to find partly damaged DNA.

DNA will quickly repair itself if only one of its two strands is damaged. But if both strands are broken, the cell will likely die. Taking advantage of lysine's ability to find single-strand damage, Alabugin attached another molecule to the lysine that would, when exposed to light, clip the second strand and kill the cell.

The molecule also controls cells' acidity, he said. Cancer cells tend to be more acidic than normal cells, so pH becomes another factor that can be used to keep damage to healthy cells to a bare minimum. —C.S.